Thier or Their: How To spell?
The word Thier is misspelled against Their, a pronoun meaning "The possessive case of the personal pronoun they; as, their houses; their country."
Word contains consecutive vowels 'EI' in between alphabets th & r is misspelled as 'IE'Wrong Spelling:  th-ie-r  Correct Spelling:  th-ei-r 
Find more wrongly spelled words of Their to spell it well.